Acute or chronic pain in patients can be treated with analgesic medicines. Such medicines can be taken orally, injected, or applied topically to the person's skin.
It can also be advantageous to deliver other types of medication topically, for example to provide localised delivery of the medication and to provide delivery of the medication over a longer period of time.
It is known from GB2517092 to apply a fluid medicament to the skin of a person using a polyurethane foam article comprising a hydrophobic polyurethane foam layer and a hydrophilic/haemophilic polyurethane foam layer. The article has at least one cavity therein, at the interface between the hydrophobic polyurethane foam layer and the hydrophilic/haemophilic polyurethane foam layer. The cavity can be filled with a fluid medicament, typically a fluid analgesic, once the article is firmly positioned in the correct anatomical selected position.
In use, the fluid medicament should be absorbed into the hydrophilic/haemophilic polyurethane foam layer, which is placed into contact with the skin of a patient. The fluid medicament will therefore be applied to the skin of the patient. The amount of fluid medicament applied to the skin of the patient can be increased by applying pressure to the hydrophobic polyurethane foam layer, typically by a physician, nurse or the patient pressing on the hydrophobic polyurethane foam layer. The hydrophobic polyurethane foam layer prevents flow of the fluid medicament away from the skin of the patient, so that when the hydrophobic polyurethane foam layer is pressed, the fluid medicament is caused to be displaced from the cavity towards the skin of the patient through the hydrophilic/haemophilic polyurethane foam layer, so that the fluid medicament is released from the article and applied to the skin of the patient.
In this manner, a fluid medicament should be applied to the patient's skin from the hydrophilic/haemophilic polyurethane foam layer.
In GB2517092 the cavity or cavities for containing the fluid medicament are formed by using one or more metal tongues. Specifically, during manufacture of the article in a mould, one or more metal tongues are positioned on top of the hydrophilic/haemophilic polyurethane foam layer to hold the hydrophilic/haemophilic polyurethane foam layer in position in the mould. The one or more metal tongues protrude from the inside of the mould to the outside of the mould. The hydrophobic polyurethane foam layer is then formed over the hydrophilic/haemophilic polyurethane foam layer and the one or more metal tongues in the mould. Once the polymerisation process has been completed, the metal tongue or tongues are removed from the resulting article. This has the effect of forming one or more cavities in the article, with the number of cavities corresponding to the number of metal tongues used. The removal of the metal tongue or tongues also means that any such cavity has a vent extending from it to the exterior of the article. The cavity or cavities can then be filled with a fluid medicament via the corresponding vent, and then the vent sealed to seal the fluid medicament in the cavity or cavities.
The present inventor has realised that the foam article disclosed in GB2517092 can be improved, to improve the application of the fluid medicament to the surface of a patient (e.g. the patient's skin), i.e. to improve targeted drug delivery using the article.